The present invention relates to a valve for use in flexible bottles or containers, the contents of which are to be supplied by means of manual pressure, and having the dual function of:
a) moderating the speed of flow; PA1 b) preventing backflow.
An area in which the valve in question finds widespread use is, for example, the pharmaceutical sector where it is extremely important that a container used to administer liquid for irrigation or medical purposes should exclusively allow the liquid to flow out from the container and prevent it from flowing back into the container for obvious hygiene/sanitary reasons. The containers in question are therefore provided with a unidirectional valve which has the function of performing the above task.
A typical example of a container where it is essential that the aforementioned valve be provided is a rubber syringe used for intestinal enemas or irrigations. In this area of use, it is necessary to moderate the force of flow of the liquid supplied. Otherwise, local pain, cramps and a tearing of the mucous tissue could result.
Implicit reference is made in the present description to this type of container even though it, as well as the abovementioned technical field, is to be regarded purely as examples which are not restrictive.
Containers of the type in question are known and it is also known that they are generally of the disposable type.
The abovementioned containers are provided, internally at the end of the supply nozzle which is connected to the actual container, with a unidirectional valve which essentially consists of thin small disc, generally made of rubber and with a thickness of about 1 mm, which has formed in it a substantially diametral incision. Edges of the disc defining the incision move apart under the effect of the pressure of the liquid inside the container, which pressure is generated by the compressive action exerted on the container made of deformable material. The liquid is therefore able to flow out from the container and the supply stops each time compression of the container is interrupted.
The known valves of this type have significant drawbacks which are linked mainly to the fact that the disc is an extremely delicate component and this negative characteristic must be taken into account both with regard to its manufacture and to the difficulties which are encountered when carrying out the preliminary treatment which the disc must undergo before being fitted on the container, such as washing and sterilization for example.
A further drawback arises from the fact that the disc must have extremely precise dimensions so as to ensure a perfect seal in particular along its edge in order to prevent the undesired seepage of liquid between the latter and the cap for closing the container. Ensuring a uniform thickness of the rubber sheet from which these discs are made, which should remain around one millimeter, represents an unresolved problem. This has meant that it has been necessary to use discs with thicknesses varying from 0.8 to 1.5 mm, thus frequently resulting in a poor sealing action of the closing caps inside which the discs are fitted.
Another significant drawback lies in the fact that fitting the disc requires long and costly manual operations, not to mention the additional operational difficulties of ensuring conditions of absolute hygiene for the manual operations.